On the one hand, bearing structure components of motor vehicle bodies, such as a front frame, a rear frame, frame side rail, as well as front and rear underbody, perform a static function, in that they absorb the vehicle weight, or the weight of individual vehicle components, like the engine. On the other hand, at least some of these components are to exhibit a defined deformation behavior in the event of extreme mechanical loads, e.g., during a vehicular collision.
The geometric configuration of individual bearing structure components in a vehicle body along with their mechanical interconnection define so-called load paths, along which impact energy that arises during a collision can be diverted in as defined a manner as possible. Load paths also serve the purpose of not just absorbing the impact energy caused by the collision, but also to keep the acting forces away from the passenger cabin, so that the latter can perform its function as a survival area for the vehicle passengers, even in the event of serious vehicular collisions.
In addition to the mechanical load requirements to be satisfied, there are constant efforts to reduce the weight of the vehicle body and motor vehicle as a whole to minimize fuel consumption. For example, DE 10 2006 052 381 A1 discloses a side frame rail for an underbody of a passenger vehicle body, of which at least a partial section is designed as a roll profile. The partial section designed as a roll profile can here incorporate a material overlap with two chambers, which can reinforce the frame side rail.
In addition, consideration can be given to the use of lightweight structural materials in body construction as a weight-saving measure. Suitable lightweight structural materials include compression-hardened components made of steel or sheet steel, as well as the use of metal sheets having a high percentage of light metals, such as magnesium or aluminum, or consist entirely of such comparatively light materials with a low density. However, such lightweight structural materials can only be conditionally used for the outside components of a motor vehicle body, such as front frames, rear frames, frame side rails or cross members, given their only moderate corrosion resistance.
Bearing structure components made of lightweight aluminum or magnesium as well as compression-hardened steel sheets must always be provided with a protective layer against corrosion for use on the outside of motor vehicles. However, thermal loads in the molding process make it virtually impossible to apply a protective layer, e.g., via zinc plating, for example for compression-hardened steel sheets. In addition, the application of a metal protective layer is always associated with an increase in weight and rise in costs.
Due to the frame profiles lying in the area that gets splashed with water and their trimmed edges, conventional front frame structures of vehicle bodies are especially susceptible to corrosion. Any flanged trim on the frame profiles must be additionally sealed.
In order to optimize the vehicle acoustics, in particular relative to noise dampening, it is further necessary to provide the underbody structure of the vehicle body with an acoustic insulation layer. The thickness of this insulation layer is here determined by the acoustic dampening requirements, so that the frame elongation determining the profile height of the front frame and running in the wet or splash water area under the vehicle floor can only be conditionally diminished in terms of its bodywork height.
In addition, it proves disadvantageous in prior art to manufacture an underbody structure by individually joining a plurality of respectively separate structural and cladding components with the vehicle body. This type of manufacture and assembly is always associated with comparatively high production effort and production costs.
Therefore, at least one object of the present invention is to provide a bearing structure arrangement of a motor vehicle body that satisfies the mechanical load requirements, has a comparatively lower weight, can be manufactured at minimized costs, and enables the creation of additional installation space inside the motor vehicle.